title: Intake and digestibility of low-quality native grass hay by beef cows supplemented with graded levels of soybean hulls.
abstract: Twelve Hereford cows and four mature, ruminally cannulated Hereford x Angus heifers were fed supplements providing either 0 (control), 1, 2, or 3 kg/d of soybean hulls and including 440 g of protein/d (cottonseed meal was used to equalize protein intake) to determine the effects of supplementation on intake and utilization of low-quality native grass hay. Cattle were housed in individual pens and fed coarsely chopped (5-cm screen) native grass hay harvested in mid-November (4.1% CP, 76.9% NDF). Hay OM intake peaked (quadratic, P = .04) at 10.1 kg/d with 1 kg of soybean hulls and decreased when 2 kg (9.8 kg/d) or 3 kg (9.1 kg/d) of soybean hulls were fed. Although hay intake decreased when soybean hulls replaced cottonseed meal, feeding 3 kg soybean hulls decreased hay OM intake by only .64 kg. Total OM digestibility increased linearly (P = .009) with added increments of soybean hulls (45.8%, 46.2%, 46.6% and 48.6% for 0 through 3 kg soybean hulls/d, respectively), indicating that hulls were more digestible than the hay. Digestibility of NDF was not affected (P = .14) by level of soybean hull supplementation, although ADF digestibility increased (linear, P = .03). Increases in OM intake and digestibility with soybean hulls combined to increase digestible OM intake (linear, P = .0001). Soybean hull supplementation increased ruminal VFA concentrations (linear, P = .04) and the molar proportion of propionate (linear, P = .006).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Oklahoma Agricultural Experiment Station, Stillwater 74078-0425.
authors.forename: S K
authors.initials: SK
authors.lastname: Martin
authors.forename: C A
authors.initials: CA
authors.lastname: Hibberd
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000254:growth & development / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D004435:Eating; D005260:Female; D005285:Fermentation; D006109:Poaceae; D012417:Rumen / Q000378:metabolism*; D013025:Glycine max
chemical_list: D004044:Dietary Proteins